20 
REVIEWS. 
supposes it very likely that he may be asked, how he knows that these 
rudimentary epizoons are really the males of the Cirripedes to which 
they attach themselves, and answers—“ that even if the whole course of the 
metamorphoses had not been known in three of the cases, the mere fact of 
these epizoons being cemented by the three terminal segments of their 
peculiar, pupal antennae, would have been sufficient to have shown that 
they belonged to the class of Cirripedes.” He was also able to demonstrate, 
in nearly every case, that these epizoons were males; and as in several 
cases the spermatozoa were developed, and in no instance, notwithstanding, 
was there a vestige of ova or ovaria, it may safely be concluded that they 
were not hermaphrodites, and, therefore, required females of some kind. 
And who would, under these circumstances, conclude that they had no 
special or sexual relation to the female Cirripedes to which they are 
attached ? This subject is most fully treated of in the text; but we give 
the above interesting, though curious facts, hoping it may be the means of 
making some of our readers take an interest in this strange class of 
creatures. In speaking of the metamorphoses of the Cirripedes, Mr. 
Darwin says as follows:— 
u I have reason to believe that the metamorphoses undergone can be reduced into 
three principal stages or heads, and that these three include all the main changes. 
First , larvse in first stage—Their shape is oval and the whole dorsal surface is evi¬ 
dently covered by a carapace ; the body exhibits no distinct articulations ; the eye 
varies considerably in the state of its development, and is of different shapes, in 
Scalpellum vulgare we see arising posteriorly to the eye a pair of minute curved 
horns directed backwards. These horns are very difficult to make out, and proba¬ 
bly could not be seen previous to first moult in any larva of smaller size than that 
of S. vulgare; but after the first moult these appear to enclose the first pair of an¬ 
tennae ; the second pair are not found until the pupal state. The mouth is more or 
less probosciformed, differing considerably in this respect in different species of 
the Lepadidae; during its very early stages there are no jaws ; but the labrum is 
furnished with some short, thick, sharp spines and some hairs. We come now to 
the three pairs of natatory legs ; the first has throughout the order only one ramus, 
whereas the two succeeding pairs are biramous. After the first moult these limbs 
are furnished with plumose spines, some curved and some straight and strong, which 
are most probably prehensile. Lastly, behind the natatory legs on the ventral sur¬ 
face, the body is much produced and terminates in a horny fork, which, after the 
first moult, becomes much elongated ; after the first moult the posterior end of the 
carapace becomes much elongated and serrated on both sides. Situated under this 
posterior prolongation of the carapace there is a swelling which apparently lies on 
the dorsal surface of the spinose and forked abdomen ; here, -when the larva is com¬ 
pressed, the cellular and oily contents of the body burst forth ; and I suspect that this 
swelling is the anus. Larva second stage —Only one specimen has hitherto been 
observed of a larva in this stage. The carapace has now greatly altered its character. 
The small internal and anterior pairs of antennae are, it would now appear, aborted ; 
the eye has commenced becoming double ; the mouth is probosciformed and does 
not differ much from its condition in the first stage ; the first pair of legs is unira- 
mous, and the two other pairs biramous; the abdomen has become much shortened, 
but still space is left for the development in the pupa of the three posterior pairs of 
legs. Larva in the third or pupal stage—On comparison with the larva in the 
second stage, the changes in external appearance and structure are not very great; 
